Fig. 1

– Physiological and pathological features of ascending thoracic aorta. The ascending trait of thoracic aorta is the first region of the artery (left picture, black square), included between aortic root, which originates from the aortic valve, and the aortic arch at the level of brachiocephalic trunk (or innominate artery). A, B In physiological conditions, the wall of the ascending thoracic aortic trait is composed of three layers (tunicae) with distinct extracellular matrix composition, structure, and biomechanics. The inner layer, tunica intima, is defined by a cell lining of endothelium (EC), interfacing with the bloodstream. The medial layer, tunica media, is composed by the functional unit of the aortic wall, consisting in contractile vascular smooth muscle cells (VSMC), wrapped in elastic extracellular matrix. The outer layer, tunica adventitia, is an ECM-rich structure with adventitial fibroblasts (Fb). The physiological localization of collagen is mainly in tunica adventitia (B, left panel, brown staining) and VSMC are small and fusiform (B, right panel). C, D In pathological conditions, the three aortic layers may undergo detrimental alterations, reported in panel C, leading to aortic wall impairments, such as massive collagen deposition also in tunica media (D, left panel, brown staining) and phenotype switching of VSMC, from contractile to larger and secretive cells (D, right panel). Green signals in VSMC: phalloidin-FITC. Immunohistochemistry, VSMC isolation and immunofluorescence methods are reported in the “Additional files”